1. Field of Invention
The present invention relates to an inflatable pneumatic bag, and more particularly, to an inflatable pneumatic bag with enhanced airtight capability.
2. Related Art
Nowadays air bubble sheets or polystyrene are widely used to wrap articles first and then load into a cardboard box to prevent the articles from impact during transportation. However, even with the air bubble sheets firmly bonded on the surfaces of the wrapped articles, the buffering effect is not satisfied. Polystyrene has a fluffy volume occupying large spaces. And besides poor microorganism-decomposed capability, polystyrene endangers humans and causes serious environment pollution with poison gas generated from incineration process. To solve the drawbacks of the air bubble sheets and polystyrene, an air-packing bag made of resin films is developed. It includes air tubes formed by thermal-sealing, and a pneumatic hole for filling air. After air is filled into the air tube through the pneumatic hole, the air-packing bag may be used as a buffer material of internal packing.
Please refer to FIG. 1, which is an explanatory diagram for an air-packing bag in the prior art before filling air; FIG. 2 shows a cross-sectional view after filling air. The air-packing bag includes two up-down stacked outer films 21a and 21b, bonded through thermal-sealing means to form a bag body, and then a pneumatic passage 22 and a air tube 23 are made by thermal-sealing means as well. Between the two outer films 21a and 21b, thermal-sealed spots 24a, 24b, 24c, 24d are utilized to attach with two inner films 25a and 25b. With the two inner films 25a and 25b bonded laterally to the outer film 21a, but with the two inner films 25a and 25b not attaching to each other, a air ingress 26 is formed therein. When the air of the pneumatic passage 22 flows through the air ingress 26 to the air tube 23 to make the pneumatic passage 22 expanded, the air in the air tube 23 will press the two inner films 25a and 25b to seal the air tube 23 for preventing the air in the air tube 23 from leaking out; for example, Japan Patent Publication No. 10-000706 “Manufacture of Synthetic Resin Bag with Check Valve”.
After said type of air-packing bag has been filled with air for a duration, the air in the air tube 23 will press the thermal-sealed spot 24b and loose off gradually, thereby generating gaps between the two outer films 21a, 21b and the two inner films 25a, 25b. Then the air in the air tube 23 will flow to the pneumatic passage 22 through the gaps generated by the loosing-off of the thermal-sealed spot 24b, leak out via the pneumatic passage 22 and make the air-packing bag malfunction. Therefore, improving the structure of the air-packing bag, to prevent from the drawbacks of poor buffering effects that the air in the air tube leaks out when the thermal-sealed spot is loosing off by air pressing, and to extend the usage lifetime of the air-packing bag, becomes an issue that the inventor of the present invention and those practicing in the art are eager to develop.